OEDs include an organic light emitting device (OLED), an organic photovoltaic cell, an organic photoconductor (OPC), or an organic transistor. For example, conventionally, a representative OLED sequentially includes a glass substrate, a transparent electrode layer, an organic layer including an emitting unit, and a reflective electrode layer.
In a structure called a bottom emitting device, the transparent electrode layer may be formed as a transparent electrode layer, and the reflective electrode layer may be formed as a reflective electrode layer. In addition, in a structure called a top emitting device, the transparent electrode layer may be formed as a reflective electrode layer, and the reflective electrode layer may be formed as a transparent electrode layer. Electrons and holes are injected into the electrode layer, and recombined in an emitting unit, thereby generating light. The light may be emitted to the substrate in the bottom emitting device, or to the reflective electrode layer in the top emitting device.
Among lights incident from the organic layer, one emitted at a critical angle or more to an interface of each layer is trapped due to total internal reflection, and only a very small amount of light is emitted. Accordingly, for example, as disclosed in the patent document 1, there is an attempt to increasing light extraction efficiency. However, a technique of extracting light that has been known so far generally premises a use of a rigid substrate such as a glass substrate, and is not effectively applied to a device using a flexible substrate having a different characteristic to the glass substrate.